First of all, that Bill James projection is almost certainly going to be wrong, because it was made before all this knee injury nonsense became public. Second, I think it’s time we stepped back and stood in awe of what a truly great player Chase Utley is. I’d argue, in fact, that he’s the fourth-best position player in the history of the Phillies, behind Mike Schmidt, Ed Delahanty, and Sliding Billy Hamilton. Of course, Hamilton and Delahanty were both 19th-century players in a game that bears only a passing resemblance to modern baseball, so depending on how you feel about Richie Ashburn and Dick Allen, a case could be made that Utley is second only to Schmidt.Chase Utley has been a full-time starter for six years. What follows are the best consecutive six-year spans, in terms of rWAR, for a Phillies position player not named Mike Schmidt since 1901.

Hamilton (1890-1895) and Delahanty (any six-year span from 1892-1901) also beat Allen by some distance, but again, how high you rate those guys depends on how highly you regard the quality of play in the turn-of-the-century National League. The point of all this, apart from being just staggeringly interesting to a nerd like me, is that Chase Utley‘s impact on the field is best described as “historic” rather than “important” or even “irreplaceable.” This might come as a surprise to some of you, because Utley (as a result of being overshadowed by the inferior, but flashier Shane Victorino, Ryan Howard, Jimmy Rollins, and Jayson Werth for most of his career) has become one of the most underrated players in the game.

Not convinced? Here’s the complete list of players who, since 2005, have compiled 30 or more WAR in the National League: Albert Pujols and Chase Utley.

So when Utley goes down with a knee injury with unspecified consequences and an unspecified return date, I think it’s right that we, as a fan base, do a collective nervous shift in our chairs.

The purpose of that little historical exercise is that however long Chase Utley is out, and whoever replaces him (unless the Phillies manage to dig up Jackie Robinson or Eddie Collins), there will be a significant drop in production. Now, I’m sure there are worse things to have in your lineup than Luis Castillo and the Seven Dwarves. When I think of one, I’ll let you know.

In all seriousness, Wilson Valdez is very valuable as a utilityman: a great defender at multiple positions. But he’s a dreadful offensive player, as I’ve said many times. Give him three weeks to replace Utley? You’re fine. Give him 600 plate appearances, however, and he’s going to kill your lineup. Castillo, at one point, was a good player, even a very good player, a three-time All-Star who thrice stole more than 40 bases in a season, has hit .300 or better seven times and has a career OBP of .368. Now, however, it’s hard to be sure. A onetime speed guy, now 35 and coming off a season where he slugged .267 in 299 plate appearances and performed so badly that his team (the Mets) was willing to pay $6 million not have him play for their team.

Valdez, one would assume, would be a better defensive player than Castillo. Valdez has had 732 plate appearances, the equivalent of a season and change, over parts of six major league seasons, and over that time he’s been a 1.9-WAR defensive player but a -0.2-WAR offensive player. Castillo famously dropped a pop-up during one of the Mets’ September collapses, and over the course of his career has been a below-replacement-level defender. However, Castillo is on base much more (Bill James projects a .361 OBP for Castillo in 2011, .312 for Valdez), and while neither hits for much power, Castillo has grounded into 120 double plays in his 15-year, 7,471-plate appearance career, one ever 62.26 plate appearances. Valdez grounds into more than twice as many double plays; at his current rate of one every 25.24 plate appearances, it would take Valdez just over 3,000 plate appearances to ground into as many double plays as Castillo has in 2 1/2 times as many trips to the plate.

The result? Castillo is likely to be a mediocre offensive player and a bad defender. Valdez is a good defender and as bad an offensive player as you’d ever hope to see. I’d rather give Castillo (assuming he makes the team) Utley’s at-bats, and use Valdez as a late-inning defensive replacement and utilityman. At any rate, if Utley misses the season with his knee issues, you’d probably lose about five marginal wins if you played Castillo every day, compared to six or more if Valdez played every day. It’s really a case of pretty bad vs. awful.

The good news? The Phillies have been dead silent on Utley’s situation, so it is possible, if rather unlikely, that he won’t miss a ton of time. Even if he’s out until Memorial Day and misses 50 games, he still put up 4.2 rWAR in 115 games last year, so maybe it’s not time to panic yet. Of course, the lack of information about the UCLA product’s knee has led to wild speculation and a projected return of anywhere from Easter to Easter 2012. Until we get some concrete news, Castillo and Valdez will have to do the best they can.

I haven’t mentioned Pete Orr, Josh Barfield, or Rule V selection Michael Martinez here because, frankly, if any of them gets more than 150 plate appearances, I’d just as soon not be watching.

The takeaway lesson at second base? Pray that Utley comes back soon, but if he doesn’t, at least Castillo and Valdez aren’t totally without value.